Carburetor



March 31, 1942.

J. 5. CULP I QARBURETOR Filed July 15, 1940 3 Sheets-Sheet 1 FIG.

K IO

ZZZ/$4 0 lllmlllll "nut/null, 1/1/1111. 1/1/11 9 INVENTOR ATTORNEY March31, 1942. S ULP 2,278,305

CARBURETOR Filed July 15, 1940 3 Sheets-Sheet 2 F1651 I FIG.4

A'IT RNEY J. S. CULP March 31, 1942.

CARBURETQR Filed July 15, 1940 3 Sheets-Sheet 3 III INVENTOR ATTORNEYPatented- Mar. 31, 1942 Q-UNITED STATES PATENT OFFICE CARBURETOR Jay S.Culp, Detroit, Mich.

Application July 15, 1940, Serial No. 345,552

8 Claims.

This invention relates to carburetor and controls therefor.

It is an object of the present invention to provide for internalcombustion engines a carburetor which will meter fuel properly at allpressures within the desired or usual pressure range.

Another object of the invention is to provide a carburetor in whichdelivery of fuel to a mixing chamber is substantially not affected oraided directly by engine created suction.

Another object of the invention is to provide a fuel metering device orcarburetor which cannot be flooded or be supplied with excess fuel byoperation of the accelerator.

Another object of the invention is to provide a new and improvedcarburetor of a character which will stop flow of fuel to the engineimmediately upon stopping'of the engine.

Another object of the invention is to provide a new and improvedcarburetor which meters both fuel and air automatically in response toengine operation or engine created suction.

Another object of the invention resides in the provision of a control orchoke for the carburetor by means of which the combustible mixture maybe enriched. without adding fuel thereto.

Another object of the invention is to provide a new and improvedcarburetor having a control or choke operable to govern engine speed.

Other objects of-the invention will become apparent from the followingdescription taken in connection with the accompanying drawings in which:

Figure 1 is a view shown in side elevation of a fuel delivery controlsystem for internal combustion engines;

Fig. 2 is a view in section of part of my carburetor, taken along theline and in the direction of the arrows 2-2 of Fig. 4;

Fig. 3 is a view, partly in section and partly in elevation, of part ofmy carburetor and taken along the lines and in the direction of thearrows 3-3 of Figs. 4 and 5;

Fig. 4 is a view shown in section of the carburetor, taken along thelines and in the direc-I tion of the arrows 4-4 of Figs. 2 and 3;

Fig. 5 is a View in side elevation of the carburetor showing operatingparts in certain positions they will assume under certain conditions ofengine operation;

Figs. 6 and '7 are views similar to Fig. 5 showing the operating partsin other positions they will assume;

Fig. 8 is an enlarged view in elevation of the carburetor showingoperating parts thereof in Fig. 9 is a vertical sectional View of thecarburetor.

Referring to the drawings by characters of reference, my fuel deliverycontrol system comprises in general a fuel and air metering device orcarburetor ill, and it also comprises a fuel delivery pump l, whichwillnot be described herein because it does not, in and of itself, forma part of the present invention. The carburetor II! includes a casing l2having a duct I3 extending therethrough, one end of which duct, as at M,may be connected and rigidly secured to a fuel intake manifold of aninternal combustion engine (not shown). In communication with the otherend of the carburetor duct I3, such as at 15, the usual air cleaner orfilter is provided and includes a sheet metal casing It which is open atits top as is usual, and encloses and supports a felt filter ll whichoverlies the carburetor intake, as at it.

Referring more. particularly to the enlarged view of Fig. 9, thecarburetor duct I3 is provided intermediate its ends with a transversewall 2t having a bore extending longitudinally therethrough transverselyto the direction of air flow to receive and in which is secured atubular fitting 2! to the outer end of which is connected a fuel vsupply line or conduit 22 leading from the outlet side of the fuel pumpH. The tubular fitting 2! is provided internally thereof with a meteringaperture and valve seat 23 which is controlled by a reciprocal valve 2 3of the so-called needle type,

i this valve, as will later be seen, being actuated in accordance withthe vacuum created by an engine controlled by my fuel delivery system.

intersecting the tubular fitting 2!, the transverse wall 26 is providedwith a bore to receive a nozzle member 25 which communicates at one endthereof, posterior to the valve seat, with the I tubular inlet fitting2| and extends longitudinally of the duct l3 to discharge the fuel intoa mixture chamber 26 communicating with the engine intake manifold.Above the fitting 2!, the wall 29 is provided with an air passage 26a,parallel with the fuel passage, the air passage 260. being incommunication With the interior of the casing l2 and being connected bya bore 2i with the interior of the fitting2l posterior and adjacent tothe valve seat 23. At this point it should be noted that fuel isdelivered to the mixing chamber 26 solely by the pump 1 I, that is, thesuction created by the engine has substantially no drawing effect on thefuel untilthe fuel has passed through valve seat aperture 23. At itsupper end the casing l2 communicates with the air filter casing I6through the opening in the lower end thereof so that air will be drawnfrom the filter casing l6, carburetor casing l2 and passages 26a and 2'0to meet with the fuel at the metering valve.

. Other air will be drawn through the duct l3 to intermingle and mixwith the fuel at the discharge end of the nozzle which as shown in Fig.2 is elongated and rounded at its upper end to reduce air flow andinduce flow to the lower discharge end of the fuel nozzle 25 for flow ofair therearound.

Within the carburetor casing I2, a chamber 28 is provided andcommunicates with the engine intake manifold, the chamber 28 beingformed in part by a movable cup-shaped member or piston which isslidably mounted in the chamber 28. Within the mixing chamber 26 issecured a tubular sleeve 29 having its outer side Wall surface spacedfrom the inner side wall surface of the duct l3 provide an annularchamber 29a which communicates with the intake manifold, and theexpansible chamber 28 is in communication with chamber 29a by connectingpassages or bores 29b and 290. The cup-shaped piston 30 is provided witha concentric cylinder 3| therein to receive a pressure responsive memberor piston 32 which is also movable in response to the sub-atmosphericpressure created by the engine and is operatively connected to the fuelmetering valve 24. The piston 32 is cup-shaped, in the present instance,and is slidably mounted in and therefore carried by the piston 30, thepiston 32 being movable with and also relative to the piston 30. Thepiston 30 is provided with an aperture 33 in an end wall 34 thereofestablishing communication with the relatively large expansible chamber28, and an opposite end wall 35 on piston 32 is provided with a tubularextension 36 which receives and to which is secured the stem 31 of themetering valve 24. Within the piston 32, a helical coil spring 38 urgesthe piston in a direction to seat the valve 24. Also a helical coilspring 39 within the expansible chamber 28 acts to urge the piston 30 ina direction to seat the metering valve. As previously mentioned thepiston 32 is slidably movable relatively to the larger piston 30, theinner wall of the larger piston having an internal shoulder 54 providinga stop for limiting relative movement of the pistons.

It will be seen that variations in suction or in the pressure created byoperation of an internal combustion engine will move the pistons whichwill in turn actuate the metering valve 24 to control delivery of fuelto the mixing chamber 26. That is, metering of the fuel will be inaccordance with operation or need of fuel for the engine.

Above the conduit wall 29 and within the duct I3 there is a butterflyvalve 33a, mounted on a shaft 340., for controlling intake of air and,as will later be seen, this valve is manually operable and alsoautomatically operable in response to engine created suction. Oppositeends of the butterfly valve shaft 34a are journaled in the side wall ofthe duct l3 and secured to one end of the shaft 34a externally of theduct 13 is an operating lever 35a. This lever 35a is provided with anarcuate slot l9 wherein is slidably received a bearing member or pin 31awhich is secured to one end of a link 38a, the other end of the link 38abeing pivotally connected by a pivot pin 39a to the upper end of a lever40.

This constitutes a loose or lost-motion connection between the lever 40and the air throttle valve operating lever, the purpose of which ishereinafter fully described. The lever 40 is pivoted at its lower end bya pin 41 to an adjustably movable fulcrum member 42 which isscrewthreaded onto a horizontally extending screw 43 by means of whichthe fulcrum member 42 may be readily and easily moved to adjust theratio of fuel and air, as will later be seen. A laterally extendingabutment 45, integral with the lever 40 intermediate the ends thereof,is loosely engaged by or in abutment with the free end of a lever-46which is mounted on a shaft 41 having one end thereof extendingexternally of the casing l2 to which an operating lever 48 is secured,the operating lever 48 being connected by suitable linkage to the usualmanual control or accelerator pedal (not shown). At its upper end, alever 50 is pivoted to the casing l2, adjacent the top thereof, by a pinor small shaft 5| and this lever 50 is of the yoke type, having a pairof spaced depending arms 52 which straddle the piston 30, the arms 52being. provided at their lower ends with opposed inwardly directed,extended portions 52a adapted to engage in a socket or external annularrecess 53 of the piston 30. One of the lever arms 52 is pivotallyconnected adjacent its lower end to the air throttle operating lever 40by thev pin 45 which, as previously mentioned, serves as an abutment forthe lever 46. Thus, piston 30 operating in response to engine createdvacuum is adapted to pivot the lever 50 and through lever 50 to pivotair throttle lever 40. During idling operation of an engine, the smallerpiston 32 is free to move by suction, to the left, facing Fig. 9, andopen the fuel metering port 23 sufiiciently to maintain combustion atidling speed operation, movement of the piston 32 to the left or in avalve opening direction being limited by the internal abutment flange 54provided in the larger piston 30. The larger piston 30 is biased to theright, Fig. 9, by the usual accelerator pedal return spring (not shown)or the pump pressure spring acting on the lever 40 through the lever 46.It will be seen that when the operating lever 48 is pivoted by operationof the foot accelerator, in a counterclockwise direction, Figs. 5 and 6,the large piston 30 will be moved to the left, Fig. 4, by the enginesuction permitting the smaller piston 32 to move to the left to furtheropenthe fuel metering port 23. Also, the pivoting of lever 40 in acounterclockwise direction by the larger piston 30 moves the butterflyvalve, through connecting link 38a toward open position. When theoperating lever 48 is moved to its extreme open position, as shown inFig. 8, the large piston 30, Fig. 9, will be stopped by abutment withits cylinder end wall cover or gasket, and further movement of thesmaller piston 32 will be limited by the internal shoulder 54 of thelarger piston so that with the parts in these positions the butterflyvalve 33a and the metering valve 24 are in full open position.

A choke operating lever 55 is provided and pivoted, as at 56, to theduct i3 externally thereof, the lever 55 like lever 35a having anarcuate slot 51 to receive the bearing member or pin 31a of theconnecting link 38a. The choke lever 55 may be operated by the usualchoke Wire 58 and this lever is adapted to change the distance oflost-motion between levers 35a and 40 to change and determine movementof the air throttlevalve of the pump II, this pump control lever 6|being' operable, as is usual, to vary the pump pressure or rate of fueldelivery.

In Figs. 4 and 5 the movable operating parts of the carburetor are shownin the positions they will assume when an engine is at rest or idle,

whereas in Fig. 6, the throttle or butterfly valve 33a is slightly openand the choke wire 58 is pulled out for cold engine starting.

In Fig. '7, with the choke still pulled out for cold engine operation,the butterfly valve 33a under control of the piston 30 is moved furthertoward full open position, but the valve 24 is in its full open positionwith the result that the fuel mixture is enriched. In the presentcarburetor, the fuel mixture is enriched by decreasing air supply by thebutterfly valve 33a. Finally in Figs. 8 and 9, the operating parts ofthe carburetor are shown in the positions they will assume when thechoke 58 is entirely in or in the leanest mixture stage or wide openthrottle position and theengine is operating at high speed, thebutterfly valve 33a and the fuel valve 24 both being fully open.

When the engine is idle, or not operating, the springs 38 and 39 holdthe valve 24 on its seat 23 and the air throttle or butterfly valve 33aclosed. Assuming now that a cold engine is started and, as is usuallythe case, the operator has pulled out the choke wire 58. As illustratedin Fig. 6 the choke lever 55 has been pivoted in a clockwise directionand has pivoted the air throttle lever 35:; in a clockwise direction toslightly open the throttle lever 33a to increase air flow capacity.Also, pivoting of the choke lever 550., places it in a position in whichit limits opening of the air throttle valve 33a. As va result, it willbe seen that the engine could not be raced or accelerated because whileadditional fuel maybe added, the air throttle valve cannot be openedsufficiently to support combustion at any engine speed above theestablished limited speed. When an efiort is made to race the engine byoperating the accelerator pedal, the excess fuel Will tend to stop theengine and the accompanying loss of engine vacuum or suction will permitthe springs 338.1161 35-3 to move the valve 24 toward its seat, thuspreventing complete stalling of the engine. It will be seen that pullingout of the choke wire serves as a speed governor. However, it is pointedout that engine power may be increased by pulling out the choke slightlyfor this moves the air throttle to decrease volume of air thus enrichingthe fuel mixture. Assuming that the temperature of the engine has nowincreased to normal operating temperature and the choke is pushed in,returning the choke lever 55 to the position shown in Fig. 5, thesmaller piston 32 operating in response to engine createdsuctionactuates the metering valve accordingly to admit the proper amount offuel to the mixing chamber 25. As previously mentioned, the range ofmovement of the smaller piston 32 is variable andis determined by theposition of the larger piston 30 which is in turn controlled by theoperators accelerator. As is well known, accelerator pedals have returnsprings to return or move the throttle to closed position. When thethrottle lever 48 is moved in the opposite direction or toward theposition thereof illustrated in dot and dash lines, Fig. 8, the smallpiston 32 is free to move to the left, Fig. 9, in response to enginecreated suction and unseat or move the valve 24 further away from itsport 23 to increase fuel supply to the engine. The air throttle lever35a, being connected to the lever Allis-also actuated by the piston 32in accordance with engine created suction. Upon stoppin of the engine,it will be seen that the springs 38 and 39 will act to move the valve 24immediately to its seat as the vacuum is lost. I

I While I have shown and described my invention in detailit is to beunderstood that the same is to be limited only by the appended claimsfor many changes may be madewithout departing from the spirit and scopeof the invention.

What I claim is:

1. In 'a carburetor for an internal combustion engine, means providingan air-fuel admixing chamber in communication with a source of suctionand fed with air and fuel from supply sources thereof, means providing acylinder in communication with said source of suction, a pair of pistonsfreely arranged one within the other and within said cylinder andmovable in one direction under the influence of said suction and in theopposite direction in opposition to said suction, valve means carried byone of said pistons for movement therewith and operable for controllingthe feeding of the fuel to said chamber, other movable valve meansoperable for controlling the feeding of the air to said chamber, levermeans operatively connected to the other of said pistons for movementtherewith, and other lever means opcratively 0on nected to saidsecond-named valve means for movement therewith and to said first-namedlever means for movement therewith.

2. In a carburetor for an internal combustion engine, means providing anair-fuel admixing chamber in communication with a source of suctionandfed, with air and fuel from supply sources thereof, means providing acylinder in communication with said source of suction, a pair of pistonsfreely arranged one within the other and within said cylinder andmovable in one direction'under the influence of said suction, springmeans operable for urging said pistons in the opposite direction inopposition to said suction, valve means carried by one of said pistonsfor movement therewith and operable for controlling the feeding of thefuel to saidchamber, other movable valve means operable for controllingthe feeding of the air to said chamber, lever means operativelyconnected to the other of said pistons for movement therewith, and otherlever means operatively connected to said second-named valve means formovement therewith and to said first-named lever means for movementtherewith.

3. In a carburetor for an internal combustion engine, means providing anair-fuel admixing chamber in communication with a source of suc saidpistons for movement therewith and operable for controlling the feedingof the fuel to said chamber, other movable valve means operable forcontrolling the feeding of the air to said chamber, lever meansoperatively connected to the other of said pistons for movementtherewith, and other lever means operatively connected to saidsecond-named valve means for movement therewith and to said first-namedlever means for movement therewith.

4. In a carburetor for an internal combustion engine, means providing anair-fuel admixing chamber in communication with a source of suction andfed with air and fuel from supply sources thereof, means providing acylinder in communication with said source of suction, a pair of hollowpistons slidably carried one within the other and within said cylinderand having their interiors in communication with each other and withsaid cylinder, said pistons being movable in one direction under theinfluence of said suction and in the opposite direction in opposition tosaid suction, valve means carried by one of said pistons for movementtherewith and operable for controlling the feeding of the fuel to saidchamber, other movable valve means operable for controlling the feedingof the air to said chamber, lever means operatively connected to theother of said pistons for movement therewith, and other lever meansoperatively connected to said second-named valve means for movementtherewith and to said first-named lever means for movement therewith.

5. In a carburetor for an internal combustion engine, means providing anair-fuel admixing chamber in communication with a source of suction andfed with air and fuel from supply sources thereof, means providing acylinder in communication with said source of suction, a pair of hollowpistons slidably carried one within the other and within said cylinderand having their interiors in communication with each other and withsaid cylinder, said pistons being movable in one direction under theinfluence of said suction, a pair of springs arranged one between saidcylinder and one of said pistons and the other between said pistons forurging said pistons in the opposite direction in opposition to saidsuction, valve means carried by one of said pistons for movementtherewith and operable for controlling the feeding of the fuel to saidchamher, other movable valve means operable for controlling the feedingof the air to said chamber, lever means operatively connected to theother of said'pistons for movement therewith, and other lever meansoperatively connected to said secend-named valve means for movementtherewith and to said first-named lever means for movement therewith,

6. In a carburetor for an internal combustion engine, means providing anair-fuel admixing chamber in communication with a source of suction andfed with air and fuel from supply sources thereof, means providing acylinder in communication with said source of suction, a pair of pistonsfreely arranged one within the other and within said cylinder andmovable in one direction under the influence of said suction and in theopposite direction in opposition to said suction, valve means carried byone of said pistons for movement therewith and operable for controllingthefeeding of the fuel to said chamber, other movable valve meansoperable for controlling the feeding of the air to said chamber, levermeans operatively connected to the other of said pistons for movementtherewith, other lever means operatively connected at one end to saidsecond-named valve means andiintermediate its ends to said first-namedlever means for movement with said second-named valve means and saidfirst-named lever means about an axis, and means selectively operablefor varying the location of said axis.

'7. In a carburetor for an internal combustion engine, means providingan air-fuel admixing chamber in communication with a source of suctionand fed with air and fuel from supply sources thereof, means providing acylinder in communication with said source of suction, a pair of pistonsfreely arranged one within the other and within said cylinder andmovable in one direction under the influence of said suction and in theopposite direction in opposition to said suction, valve means carried byone of said pistons for movement therewith and'operable for controllingthe feeding of the fuel to saidchamber, other movable valve meansoperable for controlling the feeding of the air to said chamber, a levercarried by said second-named valve means for movement therewith, asecond lever supported at one end about an axis and carried at itsopposite end by said first-named lever for movement therewith about saidaxis, and a third lever connected to the other of said pistons formovement therewith and to said second-named lever intermediate the endsof the latter for movement therewith.

8. In a carburetor for an internal combustion engine, means providing anair-fuel admixing chamber in communication with a source of suction andfed with air and 'fuel from supply sources thereof, means providing acylinder in communication with said source of suction, a pair of pistonsfreely arranged one within the other and within said cylinder andmovable in one direction under the influence of said suction and in theopposite direction in opposition to said suction, valve means carried byone of said pistons for movement therewith and operable for controllingthe feeding of the fuel to said chamber, other movable valve meansoperable for controlling the feeding of the air to said chamber, a levercarried by said second-named valve means for movement therewith andformed with a slot, a second lever supported at one end about an axisand having a pin at its opposite end engaging said slot normally at oneend of the latter to enable said second-named lever to move about saidaxis with said first-named lever, a third lever connected to the otherof said pistons for movement therewith and to said second-named leverintermediate the ends of the latter for movement therewith, and meansselectively operable for moving said first-named lever relatively tosaid second-named lever to space said pin and said slot end from eachother.

JAY s. CULP.

